If you have FileMaker Server, you can use its script scheduler to run a script each day that performs a find for such records and emails out any found.

If you leave your database open 24/7, an Install OnTimer Script step can perform that script once every 24 hours. (Convert 24 hours into seconds).

If your use of your database differs from those two options, you won't be able to perfectly do this. You can set up a script in File Options that runs every time you open the file. This script can check values in a "log" file so that this only happens the first time the file is opened on a given data to prevent multiple emailings.